Technology group Wärtsilä will supply its Wärtsilä 25 Ammonia auxiliary engine, together with a NO_x reducer (SCR) and gas valve unit (GVU), for two new 51,350 m³ capacity midsize LPG/liquid ammonia carrier vessels. The engine will support reduced emissions and improved operational efficiency, while helping the vessels meet evolving sustainability requirements. The ships are being built at Nantong CIMC Sinopacific Offshore & Engineering (SOE) shipyard in Shanghai and will be owned by a joint venture between Navigator Gas and Norway-based Amon Maritime, Navigator Amon Shipping AS. Wärtsilä will also supply the propulsion system, including a Controllable Pitch Propulsion solution designed to optimise efficiency and reliability. The order for the engines, SCR and GVU was booked by Wärtsilä in Q2 2026, whilst the order for the Controllable Pitch Propeller system was booked in Q3 2026.

As the shipping industry transitions to decarbonised operations, ammonia is emerging as a promising carbon free marine fuel capable of achieving the IMO’s net-zero-emissions target for 2050. Wärtsilä has played a leading role in developing engine solutions able to operate with alternative fuels, and already in 2023 introduced the marine sector’s first commercially available 4-stroke engine-based solution for ammonia fuel. The ammonia-fuelled engine supports the industry’s transition towards lower-emission vessel operations.

“Wärtsilä has demonstrated industry-leading capabilities in enabling future low and zero-carbon fuels to become viable. By selecting the Wärtsilä 25 Ammonia engine, we expect to dramatically reduce the ships’ environmental impact, while supporting compliance with evolving regulatory requirements,” says Mr. Kaj S. Pilemand, Director of Vessel Operations, Navigator Gas.

The ammonia engine aligns with the shipping industry’s accelerating shift towards decarbonised operations. When running on sustainable ammonia, total greenhouse gas emissions can be reduced by at least 90 percent compared to equivalent diesel engines. In addition, the Wärtsilä propulsion system optimises vessel operations by integrating the entire shaft line arrangement. The Controllable Pitch Propeller system is designed to deliver high efficiency, operational reliability, and reduced emissions.

“This project reflects the continued momentum behind carbon-neutral and zero-carbon fuels, with ammonia emerging as one key pathway. It also highlights the growing demand for flexible, propulsion solutions that support new, more sustainable operating models. In short, these vessels have been designed for lower-emission operations, and Wärtsilä’s solutions will support those ambitions,” comments Stefan Nysjö, Vice President of Power Supply, Wärtsilä Marine.

The Wärtsilä equipment is scheduled for delivery to the yard commencing in June 2027.